(Re-read). They’d been good from the go, but it was with “The Prisoner of Azkaban” that J. K. Rowling’s Harry Potter truly revealed itself as an expanding, multi-layered saga about how the past dictates the future. “The Sorcerer’s Stone” and “The Chamber of Secrets” were children’s lit at its best, but “The Prisoner of Azkaban” was the first of the novels to definitely prove that Rowling could conjure the kind of seriousness and complexity that allowed adults to embrace the series with little shame. “The Prisoner of Azkaban” is as much about grown-ups as it is about the children who are left in the shadows of grown-up drama. Missing parental authorities are standard in children’s fiction; it’s much less standard for those departed parents to become vivid characters in a book that takes place more than a decade after their death. The past is not dead, and it’s not even past, not in a place with as many ghosts as Hogwarts. It’s no coincidence that a time-traveling spell turns out to be the solution to one of the novel’s many mysteries: this is a novel about time and the tricks it plays on us. “Doing time,” after all, it’s the prisoners’ euphemism for their plight.